Taxi cost from Akibara to Tokyo Sta.

I'm quite worried about taking the JR Yamanote Line going to Tokyo Station at 5pm, transferring to the N'ex for our flight back home. My wife and I are expecting to be carrying 2 large trolleys, a carry-on trolley and a camera bag. I'm not even sure if we can carry these on the Yamanote Train.

Since I'm planning to buy the Ne'x Suica Package (2 way), I'm thinking of just getting a taxi from Akihabara to Tokyo Station, then Ne'x to the airport. How much would that roughly cost considering the distance and probably traffic?

Its 2.5-3km between stations, depending on the route, which will cost between 900-1100 yen by regular taxi. It would be possible to take your luggage on the trains if you wish to brave it though, but a taxi would be more convenient.